Simulation And Optimization Of Microcrystalline Silicon Germanium Solar Cells

Nowadays,the main solar energy supply in the power system is crystalline silicon solar cells.Because of the difficulty in increasing the conversion efficiency and decreasing the cost,the on-grid price of photovoltaic is much higher than that of traditional energy.In contrast,silicon based thin film solar cells have the advantages of low cost and good response for low intensity light,which can be used to further reduce the cost of grid-connected photovoltaic.However,its efficiency is still relatively low,which is obstacle to its development.Hydrogenated microcrystalline silicon germanium(?c-SiGe:H)is a new type of narrow gap material,a promising candidate for the solar cell absorber,which has been developed in recent years.?c-SiGe:H has certain advantages such as high absorption coefficient and good response for infrared light,which can be used as the bottom cell of silicon-based tandem solar cells.Therefore,the application of the ?c-SiGe:H can effectively improve the photoelectric conversion efficiency silicon-based tandem solar cells.In this paper,a computer simulation method was used to simulate the ?c-SiGe:H solar cells.First,the ?c-SiGe:H solar cell models with different intrinsic layers have been established by wxAMPS.Comparing the constant band gap ?c-SiGe:H solar cell with the same Ge content,the efficiency of the cell with graded band gap was increased by 36%.Based on the traditional linear gradient structure,a new curve graded band gap structure was put forward and optimized,of which the conversion efficiency was 13.82%.Then,the amorphous silicon germanium(a-SiGe:H)buffer layer was added to the p/i interface of this cell.The buffer layer was optimized by adjusting the germanium content and the thickness.The short-circuit current and the open circuit voltage of the solar cell were further improved,and the conversion efficiency was increased by 4.5%.Finally,an innovative a-Si:H/a-SiGe:H/?c-Si:H/?c-SiGe:H quadruple junction solar cell model was established.The improved model of ?c-SiGe:H solar cell was used as the bottom cell of the quadruple junction solar cell,leading to a high conversion efficiency of the quadruple junction solar cell of 24.8%.Comparing with the same Ge content ?c-SiGe:H cell and the ?c-Si:H cell as the bottom cell,the efficiency of the quadruple junction solar cell could be increased by 8.7% and 16.7%,respectively.The results show the potential application of ?c-SiGe:H in silicon-based thin film solar cells.